From: Borislav Petkov <bp@alien8.de>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: x86@kernel.org, linux-sgx@vger.kernel.org,
linux-kernel@vger.kernel.org,
Sean Christopherson <sean.j.christopherson@intel.com>,
Andy Lutomirski <luto@amacapital.net>,
Jethro Beekman <jethro@fortanix.com>,
akpm@linux-foundation.org, andriy.shevchenko@linux.intel.com,
asapek@google.com, cedric.xing@intel.com,
chenalexchen@google.com, conradparker@google.com,
cyhanish@google.com, dave.hansen@intel.com,
haitao.huang@intel.com, josh@joshtriplett.org,
kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com,
ludloff@google.com, luto@kernel.org, nhorman@redhat.com,
npmccallum@redhat.com, puiterwijk@redhat.com,
rientjes@google.com, tglx@linutronix.de, yaozhangx@google.com
Subject: Re: [PATCH v33 15/21] x86/vdso: Add support for exception fixup in vDSO functions
Date: Mon, 29 Jun 2020 19:10:22 +0200 [thread overview]
Message-ID: <20200629171022.GC32176@zn.tnic> (raw)
In-Reply-To: <20200617220844.57423-16-jarkko.sakkinen@linux.intel.com>
On Thu, Jun 18, 2020 at 01:08:37AM +0300, Jarkko Sakkinen wrote:
...
> intended benefit of massaging GCC's inlining algorithm is unlikely to
> realized in the vDSO any time soon, if ever.
That is a very good explanation and I would prefer if it would be in a
sgx-specific README or so instead of it getting lost in git...
> +bool fixup_vdso_exception(struct pt_regs *regs, int trapnr,
> + unsigned long error_code, unsigned long fault_addr)
> +{
> + const struct vdso_image *image = current->mm->context.vdso_image;
> + const struct vdso_exception_table_entry *extable;
> + unsigned int nr_entries, i;
> + unsigned long base;
> +
> + /*
> + * Do not attempt to fixup #DB or #BP. It's impossible to identify
> + * whether or not a #DB/#BP originated from within an SGX enclave and
> + * SGX enclaves are currently the only use case for vDSO fixup.
> + */
So this is all fine and dandy but nowhere do I see the code doing:
if (am_I_an_sgx_enclave(tsk))
fixup_vdso_exception()
because that vDSO exception fixup, albeit it looking kinda generic, is
SGX-only for now. So it should be designed to run only for SGX enclaves
for now.
Also, is there any particular reason for fixup_vdso_exception() to be in
arch/x86/entry/vdso/extable.c instead of in arch/x86/mm/extable.c?
I mean, it gets called by traps.c so it looks like normal kernel code to
me or am I missing some vdso magic?
And built only when CONFIG_INTEL_SGX is enabled.
And so on...
...
> diff --git a/arch/x86/entry/vdso/extable.h b/arch/x86/entry/vdso/extable.h
> new file mode 100644
> index 000000000000..aafdac396948
> --- /dev/null
> +++ b/arch/x86/entry/vdso/extable.h
> @@ -0,0 +1,29 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __VDSO_EXTABLE_H
> +#define __VDSO_EXTABLE_H
> +
> +/*
> + * Inject exception fixup for vDSO code. Unlike normal exception fixup,
> + * vDSO uses a dedicated handler the addresses are relative to the overall
> + * exception table, not each individual entry.
> + */
> +#ifdef __ASSEMBLY__
> +#define _ASM_VDSO_EXTABLE_HANDLE(from, to) \
> + ASM_VDSO_EXTABLE_HANDLE from to
> +
> +.macro ASM_VDSO_EXTABLE_HANDLE from:req to:req
> + .pushsection __ex_table, "a"
> + .long (\from) - __ex_table
> + .long (\to) - __ex_table
> + .popsection
> +.endm
> +#else
> +#define _ASM_VDSO_EXTABLE_HANDLE(from, to) \
> + ".pushsection __ex_table, \"a\"\n" \
> + ".long (" #from ") - __ex_table\n" \
> + ".long (" #to ") - __ex_table\n" \
> + ".popsection\n"
> +#endif
> +
> +#endif /* __VDSO_EXTABLE_H */
> +
.git/rebase-apply/patch:122: new blank line at EOF.
+
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-06-29 19:39 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-17 22:08 [PATCH v33 00/21] Intel SGX foundations Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 01/21] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-06-22 17:37 ` Borislav Petkov
2020-06-25 1:25 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 02/21] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-06-24 13:04 ` Borislav Petkov
2020-06-24 14:34 ` Sean Christopherson
2020-06-25 1:28 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 03/21] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-06-25 8:59 ` Borislav Petkov
2020-06-25 15:34 ` Sean Christopherson
2020-06-25 16:49 ` Borislav Petkov
2020-06-25 20:52 ` Jarkko Sakkinen
2020-06-25 21:11 ` Borislav Petkov
2020-06-26 13:34 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 04/21] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 05/21] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 06/21] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 07/21] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 08/21] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-06-25 10:14 ` Borislav Petkov
2020-06-25 20:11 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 09/21] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen
2020-06-25 17:06 ` Borislav Petkov
2020-06-25 20:55 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 10/21] mm: Introduce vm_ops->may_mprotect() Jarkko Sakkinen
2020-06-25 17:14 ` Borislav Petkov
2020-06-25 17:30 ` Matthew Wilcox
2020-06-25 18:06 ` Sean Christopherson
2020-06-25 22:40 ` Jarkko Sakkinen
2020-06-25 22:26 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 11/21] x86/sgx: Linux Enclave Driver Jarkko Sakkinen
2020-06-25 17:23 ` Borislav Petkov
2020-06-25 18:34 ` Sean Christopherson
2020-06-25 18:45 ` Borislav Petkov
2020-06-26 14:19 ` Jarkko Sakkinen
2020-06-25 20:21 ` Jarkko Sakkinen
2020-06-25 20:25 ` Borislav Petkov
2020-06-26 13:40 ` Jarkko Sakkinen
2020-06-25 18:53 ` Borislav Petkov
2020-06-26 14:17 ` Jarkko Sakkinen
2020-06-26 9:14 ` Borislav Petkov
2020-06-26 14:16 ` Sean Christopherson
2020-06-26 14:20 ` Borislav Petkov
2020-07-03 23:04 ` Jarkko Sakkinen
2020-07-03 3:09 ` Jarkko Sakkinen
2020-06-26 15:34 ` Borislav Petkov
2020-07-04 0:13 ` Jarkko Sakkinen
2020-10-26 21:26 ` Dave Hansen
2020-10-27 1:52 ` Jarkko Sakkinen
2020-10-27 10:05 ` Borislav Petkov
2020-10-27 15:20 ` Dave Hansen
2020-10-27 15:37 ` Borislav Petkov
2020-06-27 17:43 ` Borislav Petkov
2020-06-29 15:27 ` Sean Christopherson
2020-06-29 15:37 ` Borislav Petkov
2020-07-04 1:43 ` Jarkko Sakkinen
2020-07-07 1:38 ` Sean Christopherson
2020-07-07 3:29 ` Jarkko Sakkinen
2020-07-04 1:42 ` Jarkko Sakkinen
2020-07-02 3:59 ` Sean Christopherson
2020-07-04 3:31 ` Jarkko Sakkinen
2020-09-02 3:06 ` Haitao Huang
2020-09-02 16:10 ` Sean Christopherson
2020-09-02 18:40 ` Haitao Huang
2020-09-04 12:01 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation Jarkko Sakkinen
2020-06-29 16:02 ` Borislav Petkov
2020-06-29 22:04 ` Sean Christopherson
2020-06-30 8:49 ` Borislav Petkov
2020-06-30 14:20 ` Sean Christopherson
2020-06-30 17:13 ` Andy Lutomirski
2020-07-02 20:47 ` Dr. Greg
2020-07-03 2:43 ` Jarkko Sakkinen
2020-07-03 2:38 ` Jarkko Sakkinen
2020-07-03 2:32 ` Jarkko Sakkinen
2020-07-03 2:55 ` Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 13/21] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 14/21] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 15/21] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-06-29 17:10 ` Borislav Petkov [this message]
2020-06-30 6:00 ` Sean Christopherson
2020-06-30 8:41 ` Borislav Petkov
2020-06-30 14:55 ` Sean Christopherson
2020-06-30 16:48 ` Andy Lutomirski
2020-06-30 17:23 ` Sean Christopherson
2020-07-02 12:52 ` Thomas Gleixner
2020-06-17 22:08 ` [PATCH v33 16/21] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 17/21] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 18/21] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 19/21] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 20/21] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-06-17 22:08 ` [PATCH v33 21/21] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
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